The Exemplary Clarity of the Five Proofs of the Existence of God

Edward Feser has a definite gift for making fairly abstruse philosophical material accessible to readers from outside the academic world, without compromising the rigor of the arguments or omitting challenging details. As scholarly virtues go, this is one of the rarer ones—in part because it takes considerable patience both to acquire and to practice, and in part because it requires a genuine desire to entrust difficult ideas to those from whom they are typically withheld. Perhaps the best example of this gift in action hitherto was his 2006 volume Philosophy of Mind: A Beginner’s Guide (at least, speaking for myself, I have both recommended it to general readers and used it with undergraduates, in either case with very happy results). But this present volume, Five Proofs of the Existence of God, is no less substantial an achievement. In it, Feser has undertaken to explain and defend several of the most demanding traditional arguments for the reality of God, as thoroughly as possible, in a way that communicates their internal coherence to readers who may have no special formal training in philosophy, but who are willing to follow an argument to its end.

It is also a virtue on Feser’s part that the only God he cares to argue for is the God of “classical theism.” He does not waste any attention on debates (of the kind all too depressingly common in Anglophone philosophy of religion) over the possible reality of a single “supreme being” who exists alongside other, lesser beings, on the same ontological plane (so to speak), and set off from them only by virtue of his “maximal greatness,” or some other property that makes him far larger and far older than all other things. Feser clearly grasps that, even if one could prove that such a being exists, this would bring us no nearer to an understanding of the true source of all reality (which for monotheists, presumably, is what the word “God” ideally refers to), but would merely provide us with one more entity whose existence must be accounted for. And so he concerns himself only with the God common to the intellectual traditions of all the great theistic creeds: the transcendent and infinite wellspring of all being, unique, eternal, simple, admitting of no division within himself between essence and existence, the absolute actuality upon which all finite and conditioned things depend, and therefore the only possible “sufficient reason” for the existence of anything at all.

One might imagine from the book’s title that it is an extended treatment of Thomas’s quinque viae, and of course Feser identifies himself primarily as a Thomist. But, in fact, the five proofs addressed here are drawn from a variety of ancient, medieval, and early modern sources, and constitute what Feser deems to be the five strongest traditional arguments for the reality of a transcendent God. The first of these—the so-called “Aristotelian” proof—proceeds from the fact of “motion” (or, better, “change”) from potency to actuality in all finite things, and eventuates in a necessary reduction of all such motion to a first unmoved mover. Feser is especially good here at explaining that the causal deduction advanced by this argument points not to an initial first efficient cause within a sequence of consecutive effects, but rather to the sole sustaining and enduring unconditioned condition that in every instant allows for the actuality of finite and mutable things. The second argument is a “Neoplatonic” proof that proceeds from the reality of the composite (and hence conditional) nature of all existing things toward a transcendent One—Being as absolute and infinite simplicity—apart from which the necessary conditions for the reality of any finite thing could never obtain.

The third argument Feser calls the “Augustinian” proof; it proceeds from the reality of universals, propositions, abstract truths, logical possibilities, and so forth, to that reality in which all these things must necessarily subsist: which (so the argument at last concludes) must be the divine intellect. This Feser denominates the “scholastic” theory of the forms (as opposed to the Platonic or Aristotelian), though that is a somewhat arbitrary designation; it would be more historically accurate to speak of it as the “Neoplatonic” or “patristic” theory, which was admittedly inherited and preserved by the best of scholastic tradition, but which long antedated the Middle Ages. Whatever the case, though, Feser manages to bring out the logical force of this approach better than most of its other expositors.

The fourth argument is the “Thomistic” proof, which—as scarcely needs be said—proceeds from the logical distinction of essence and existence in all finite, composite, or conditioned things to the necessary reality of the perfect convertibility of essence and existence in the one divine actus essendi subsistens. And the fifth—the “rationalist” proof—is at once a defense of the Principle of Sufficient Reason and a demonstration that, pursued to its ultimate logical terminus, this principle leads back to the God of classical theism, as the sole possible explanation of everything that has the rationale for its existence outside itself.

In a sense, of course, all but the third of these proofs are differing versions of the same basic argument: a deductive ascent from the caused to the first cause, the conditioned to the unconditioned, the contingent to the absolute, the explicanda to the primum explicans. This, however, is actually the chief strength of the book, as each argument fortifies every other, and progressively elucidates the single grand logical intuition uniting them all. Perhaps the most obliging aspect of Feser’s approach is the somewhat scholastic method he has devised for himself. Each of the five proofs at issue is first laid out, step by step, patiently and fully, but concisely as well; each exposition is then recapitulated by being distilled into a series of numbered propositions, leading to an inevitable conclusion; and then each proof is defended against those objections most typically raised against it. The book concludes with a somewhat more general treatment of the relation between God and world in the metaphysical tradition of classical theism, as well as a more deliberate consideration and refutation of the perennially most persistent critiques of that tradition. Much of this repeats points already made earlier in the text, but (as anyone who teaches can attest) that is a virtue of any text attempting to convey a larger philosophical vision to those for whom it may as yet be rather new. And these pages bring out with special clarity that the “metaphysical” God of classical theism must, if our reasoning is consistent, be invested with all the “personal” attributes of the God of faith—most particularly, intellect and will.

If I have any quibbles with the book as a whole, they are of a somewhat marginal and oblique kind. For instance, I think Feser could take his defense of the Principle of Sufficient Reason even further than he does, especially in dealing with the recently popular objection from the possibility of a “grand conjunctive proposition” and the modal quandaries this possibility supposedly raises. Not that Feser fails to point out many of the principal flaws in the argument, and he is right that ultimately it depends upon the willful fabrication of a false dilemma, one that weirdly reifies propositions as though they were subsistent substances. But, at the same time, there are genuine questions of necessity and contingency to which the argument points, however feebly, and so perhaps Feser would have done well to note that, even in its most thoroughly worked-out form, it is an argument that fails to distinguish between intrinsic necessity and consequent necessity. He might even have noted that, in a sense, it can be inverted as an argument for the necessary reality of an infinite and simple God who is the actuality of all Being as such, and who therefore is alone able to resolve the tension between necessity and contingency in any explanation of the rationale for creation.

By the same token, Feser takes very much the Thomist line regarding the issue of whether God has created—or must logically create—the best of all possible worlds. He is right, of course, that the very notion of such a world is logically contradictory if we assume (as many do) that the best world would consist in a specific ideal sum (or perhaps inexhaustible abundance) of discrete good things or pleasant qualities. At the same time, it must also be the case that the God of classical theism never acts arbitrarily, by way of some sort of purely voluntarist liberty, and so it must be the case that, if God creates one world rather than another, he does so according to a rationale, and moreover that this must be a rationale best in keeping with the highest Good of the divine nature. While he touches upon this, perhaps it would have been as well on Feser’s part to spend a few more pages on the difference between the artificial notion of a “best possible world” qua possible world and the one world that best realizes a specific ultimate good beyond itself, and to fortify this point with an explanation of the “intellectualist” model of freedom. At least, this might help to guard against an inadvertent anthropomorphization of the divine will on his readers’ parts.

These, however, are mere minor cavils, and have as much to do with my own preoccupations as with the larger issues dealt with in this book. In sum, Feser’s is an admirable achievement, and this book can be recommended for the classroom quite vigorously—but also, happily, not only for the classroom. It accomplishes much in a fairly compact space, and does so with exemplary clarity. In fact, it is among the best such volumes currently available in English.